What is Birretum, Birretus?

Alternative Forms: Birretum | Birretus
Legal Definition
Or BIRRETUS. A cap or coif used formerly in England, by judges and sergeants at law. Spelm. h. t.; Cunn. Dict. Vide Coif.
-- Bouviers Law Dictionary
Legal Definition
A cap or coif used formerly in England by judges and serjeants at law. Spelman.
-- Black's Law Dictionary
Legal Definition
The cap of a judge or sergeant.
-- Ballentine's Law Dictionary